Association of phosphorylated serine/arginine (SR) splicing factors with the U1-small ribonucleoprotein (snRNP) autoantigen complex accompanies apoptotic cell death.
Proteins subject to proteolysis or phosphorylation during apoptosis are commonly precipitated by autoantibodies found in the serum of patients with systemic lupus erythematosus (SLE). We screened a panel of murine monoclonal and human monospecific sera reactive with known autoantigens for their ability to selectively precipitate phosphoproteins from apoptotic Jurkat T cell lysates. Sera known to recognize the U1-small nuclear ribonucleoprotein (snRNP) complex (confirmed by their ability to precipitate U1-snRNA) selectively precipitated a phosphoprotein complex (pp54, pp42, pp34, and pp23) from apoptotic lysates. Monoclonal antibodies reactive with U1-snRNP proteins precipitated the same phosphoprotein complex from apoptotic lysates. The phosphorylation and/or recruitment of these proteins to the U1-snRNP complex is induced by multiple apoptotic stimuli (e.g., Fas ligation, gamma irradiation, or UV irradiation), and is blocked by overexpression of bcl-2. The U1-snRNP-associated phosphoprotein complex is immunoprecipitated by monoclonal antibodies reactive with serine/arginine (SR) proteins that comprise a structurally related family of splicing factors. The association of phosphorylated SR proteins with the U1-snRNP complex in cells undergoing apoptosis suggests a mechanism for regulation of alternative splicing of apoptotic effector molecules.
Utz
P J
PJ
Department of Medicine, Division of Rheumatology, Immunology, and Allergy, Brigham & Women's Hospital, Boston, Massachusetts 02115, USA.
Hottelet
M
M
van Venrooij
W J
WJ
Anderson
P
P
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions / Q000276:immunology*; D017209:Apoptosis / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D019169:Jurkat Cells; D046911:Macromolecular Substances; D051379:Mice; D009687:Nuclear Proteins / Q000276:immunology*; D010750:Phosphoproteins / Q000276:immunology*; D012326:RNA Splicing / Q000276:immunology; D012342:RNA, Small Nuclear / Q000276:immunology; D016601:RNA-Binding Proteins / Q000276:immunology*; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology*; D012261:Ribonucleoproteins; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000276:immunology; D019014:fas Receptor / Q000276:immunology
D000911:Antibodies, Monoclonal; D001324:Autoantigens; D007106:Immune Sera; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; D017412:Ribonucleoprotein, U1 Small Nuclear; D012261:Ribonucleoproteins; C499372:SRSF2 protein, mouse; D019014:fas Receptor; C073288:SRSF2 protein, human; D000068103:Serine-Arginine Splicing Factors